DE602005006157T2 - STABILIZED 99mTC COMPOSITION - Google Patents

Abstract

The present invention relates to stabilised 99mTc radiopharmaceutical compositions of the ligand tetrofosmin, which include an ascorbic acid or ascorbate radioprotectant, in the absence of an antimicrobial preservative. The invention also provides lyophilised kits suitable for the bulk preparation of multiple unit patient doses of 99mTc-tetrofosmin metal complexes. Also disclosed are unit doses of 99mTc-tetrofosmin, together with processes for preparing such unit doses from the lyophilised bulk vial.

Description

Field of the invention

The present invention relates to stabilized ^99m Tc radiopharmaceutical compositions of ^99m Tc-tetrofosmin, which is a derivative of ascorbic acid or ascorbate radioprotectant (Radioprotectant) include, in the absence of an antimicrobial preservative. Lyophilized kits suitable for mass-preparation of multiple patient dosage units of the ^99m Tc radiopharmaceutical ^tetrofosmin composition are also disclosed, along with methods of preparing such dosage units from the bulk lyophilized vial.

Background of the invention

Diagnostic imaging radiopharmaceuticals based on the radioisotope technetium-99m ( ^99m Tc) are well known in a variety of clinical diagnostics, including studies of functional (e.g., renal) nature and perfusion (especially of the heart and brain). Since the radioisotope ^99m Tc has a half-life of six hours, such ^99m Tc radiopharmaceuticals are usually prepared from so-called "kits".

These kits for the preparation of ^99m Tc radiopharmaceuticals allow the user to stock up non-radioactive, lyophilized vials containing the necessary reagents to reconstitute with ^99m Tc pertechnetate (TcO ₄ ^- ) from a reserve of ^99m Tc are designed to give the desired sterile ^99m Tc radiopharmaceutical in a simple manner. A sterile solution of ^99m Tc pertechnetate in isotonic saline is obtained by elution of a technetium generator with sterile saline, as known in the art.

• (i) einen Liganden, der einen Metallkomplex mit ^99mTc bildet,
• (ii) ein biokompatibles Reduktionsmittel, das in der Lage ist, Pertechnetat, also Tc(VII), zum niedrigeren Oxidationszustand des gewünschten ^99mTC-Metallkomplexprodukts zu reduzieren.

Kits for the preparation of ^99m Tc radiopharmaceuticals typically contain:

• (i) a ligand forming a metal complex with ^99m Tc,
• (ii) a biocompatible reducing agent capable of reducing pertechnetate, ie Tc (VII), to the lower oxidation state of the desired ^99m TC metal complex product.

The biocompatible reducing agent for ^99m Tc pertechnetate is typically stannous ion, ie Sn (II). The kit may contain additional excipients, e.g. Weak chelators (such as gluconate, glucoheptonate, tartrate, phosphonate or EDTA); stabilizers; pH regulators; Buffer; Solubilizers or fillers (such as mannitol, inositol or sodium chloride) to facilitate handling and lyophilization of kit components. For ease of storage and distribution, the non-radioactive kits are usually provided freeze-dried in a sterile vial with closure. In addition, the lyophilized formulation allows the end user to easily reconstitute with sterile ^99m TC pertechnetate in saline to give the desired sterile, injectable ^99m Tc radiopharmaceutical for human use. The shelf life of the non-radioactive technetium kit may be several months.

Radiopharmaceutical compositions may be affected by radiolysis, particularly of the solvent (typically water) with the consequent generation of highly reactive free radicals which, upon reconstitution, may disassemble one or more components of the kit composition. The use of radiation stabilizers or free radical scavengers is known to assist in suppressing such decomposition. Significantly, free radical scavengers are selected from known classes of antioxidant compounds. Ascorbic acid and ascorbates, which act as stabilizers for tin-containing non-radioactive kits for the preparation of ^99m Tc radiopharmaceuticals, are described in ^U.S.Pat US 4,364,920 and have subsequently found widespread use in radiopharmaceutical ^99m Tc preparations. In US 4,233,284 Gentisic acid stabilizers for ^99m Tc radiopharmaceuticals are disclosed. Para-aminobenzoic acid (PABA) and related stabilizers for radiopharmaceutical ^99m Tc preparations are described in ^U.S.P. US 4,451,451 disclosed.

The Myoview ^™ kit is a 10 ml vial containing the following lyophilized formulation: tetrofosmin 0.23 mg Tin chloride dihydrate 30 μg Dinatriumsulfosalicylat 0.32 mg Sodium D-gluconate 1.0 mg sodium 1.8 mg pH at reconstitution 8.3 to 9.1, which formulation is sealed under nitrogen gas USP / NF in a 10 ml glass vial and after reconstitution with sterile sodium ( ^99m Tc) pertechnetate injection USP / Ph. Eur. gives a solution containing the radiopharmaceutical ^99m Tc-tetrofosmin for imaging from the heart. Consequently, the Myoview ^TM kit contains no radiation protection.

An injectable or "conjugate" model of Myoview ^™ has been marketed in Japan since 1997. This "conjugate" form comprises the pre-formed ^99m Tc-tetrofosmin-technetium complex in aqueous solution in a syringe vial, ie a vial with a separate flask and a separate needle designed to be assembled immediately to give a syringe containing the radiopharmaceutical. The Myoview ^™ "conjugate" solution contains ascorbic acid at a concentration of 1.36 mg / ml (7.7 mmolar).

Bastien, et al. [Nucl. Med. Comm., 20, 480, abstract 84 (1999)] indicate that the order of addition of saline and pertechnetate to the Myoview ^™ kit can affect the radiochemical purity (RCP: Radiochemical Purity) of ^99m Tc tetrofosmin. Furthermore, Murray, et al. [Nucl. Med. Comm., 21, 845-849 (2000)] that the presence of too much nitrogen gas in the headspace of the Myoview ^™ vial during reconstitution may result in variable RCP results due to unwanted radiochemical impurities. Murray, et al., And the instructions for use on the pack of the Myoview ^™ kit, explain that air is deliberately drawn into the vial during reconstitution to circumvent these problems. This is achieved by removing 2 ml of headspace gas when a vent needle is placed so that 2 ml of air is drawn into the vial. It is believed that the cause of the problem is reductive autoradiolysis and that ingestion of oxygen inhibits this decomposition.

Patel, et al. [J. Nucl. Med. Technol., 26 (4), 269-273 (1998)] present the results of a study of commercially available Myoview ^™ vials and conclude that reconstitution is twice the manufacturer's upper limit for radioactivity (to to 18 GBq of ^99m Tc), but they do not clarify the limitations of the ^99m Tc pertechnetate generator eluate used. Allegedly, such higher levels of radioactivity provide the benefits of less exposure to personnel (one preparation rather than multiple preparations) and less variation in QC results. Indeed, Murray reports, inter alia (supra), that the use of radioactive concentrations exceeding those given in the instructions for use on the Myoview ^™ package results in poor RCP results.

• (i) einen ^99mTc-Metallkomplex;
• (ii) ein Strahlenschutzmittel, welches Ascorbinsäure, para-Aminobenzoesäure oder Gentisinsäure, oder ein Salz davon mit einem biokompatiblen Kation umfasst;
• (iii) eines oder mehrere antimikrobielle Konservierungsmittel der Formel (I):

wobei R für C_1-4-Alkyl steht,
und M für H oder ein biokompatibles Kation steht. WO 02/053192 discloses stabilized radiopharmaceutical compositions comprising:

• (i) a ^99m Tc metal complex;
• (ii) a radiation protection agent comprising ascorbic acid, para-aminobenzoic acid or gentisic acid, or a salt thereof with a biocompatible cation;
• (iii) one or more antimicrobial preservatives of formula (I):

where R is C _1-4 -alkyl,
and M is H or a biocompatible cation.

The examples WO 02/053193 include the preparation of stabilized ^99m Tc-tetrofosmin complex compositions via the addition of Radiation Protection Solution and antimicrobial preservative solution to conventional Myoview ^™ kits. No specific examples of lyophilized kits containing both tetrofosmin and a radioprotectant are disclosed in U.S. Patent Nos. 5,496,066 and 4,237,237 WO 02/053192 disclosed.

The present invention

The present invention relates to kits for the preparation of stabilized ^99m Tc-tetrofosmin radiopharmaceutical compositions, together with a method of preparing ^99m Tc-tetrofosmin dosage units.

To solve the problem of prolonged availability of a post-reconstitution radiomedical ^99m TC agent, the initial level of ^99m Tc radioactivity upon reconstitution must be high, because, because of the six-hour half-life of ^99m Tc, half of the radioactivity, which is used to generate the diagnostic image, is lost via radioactive decay every six hours, and therefore remains after the lapse of twelve hours of only the original radioactivity. Such high levels of radioactivity over extended periods of time may raise significant radiolysis problems with the radiopharmaceutical ^99m Tc composition.

Therefore, the composition of the present invention contains a radiation protection agent. The ^99m Tc tetrofosmin active ingredient is susceptible either to degradation by the reducing action of the reducing agent (which is present to aid in performing labeling with ^99m Tc) or to radiolysis. By using the stabilized compositions of the present invention, it is possible to extend useful life after radiolabelling even at elevated ^99m Tc radioactivity levels.

Detailed description of the invention

• (i) Tetrofosmin;
• (ii) ein Strahlenschutzmittel, ausgewählt aus Ascorbinsäure oder einem Salz derselben mit einem biokompatiblen Kation;
• (iii) ein biokompatibles Reduktionsmittel;
• (iv) ein pH-Regulierungsmittel in einer Menge, die wirksam ist, um zu gewährleisten, dass, bei Rekonstitution des Kits mit Kochsalzlösung, die sich ergebende Lösung einen pH-Wert im Bereich von 8,0 bis 9,2 aufweist;

mit der Maßgabe, dass weder der Kit noch die radiopharmazeutische ^99mTc-Tetrofosmin-Zusammensetzung ein antimikrobielles Konservierungsmittel enthält.In a first aspect, the present invention provides a lyophilized, non-radioactive kit which, when reconstituted with ^99m Tc pertechnetate solution, yields a stabilized radiopharmaceutical ^99m Tc tetrofosmin composition, the kit comprising a formulation comprising:

• (i) tetrofosmin;
• (ii) a radiation protection agent selected from ascorbic acid or a salt thereof with a biocompatible cation;
• (iii) a biocompatible reducing agent;
• (iv) a pH control agent in an amount effective to ensure that upon reconstitution of the saline kit, the resulting solution has a pH in the range of 8.0 to 9.2;

provided that neither the kit nor the radiopharmaceutical ^99m Tc tetrofosmin composition contains an antimicrobial preservative.

der in dem im Handel vertriebenen ^99mTc-Kit mit dem Namen Myoview^TM verwendet wird, mit dem die Zubereitung von ^99mTc-Tetrofosmin, also ^99mTc(O)₂(tetrofosmin)₂ ⁺, erfolgt.By the term "tetrofosmin" is meant the illustrated ether-substituted diphosphine chelating agent 1,2-bis [bis (2-ethoxyethyl) phosphino] ethane:

the ^99m in the commercially sold Tc kit called ^Myoview is used with the preparation of ^99m Tc-tetrofosmin, that ^99m Tc (O) ₂ (tetrofosmin) ₂ ^+, takes place.

As a "radiation protection" is a connection which inhibits degradation reactions such as redox processes, that highly reactive free radicals, such as oxygen-containing free radicals, which come from the radiolysis of water, are captured. Suitably, the radiation protection agents of the present Invention of ascorbic acid and salts thereof with a biocompatible cation.

Under the term "biocompatible Cation "is a to understand a positively charged counterion that is a salt with a ionized, negatively charged anionic group forms, wherein the positively charged counterion at the required dosage not is toxic and therefore suitable for administration to the body of a mammal, especially the body of a human, is suitable. Examples of suitable biocompatible cations belong: the alkali metals sodium and potassium, the alkaline earth metals calcium and magnesium and also the ammonium ion. Preferred biocompatible Cations are sodium and potassium, with sodium being a particular preference is given.

Of the Term "biocompatible Reducing agent "referred a reducing agent used to reduce Tc (VII) pertechnetate to lower oxidation states Technetium is not good at the required dosage is toxic and therefore suitable for administration to the body of a mammal, especially to the body of a human, is suitable. Suitable reducing agents include: sodium dithionite, Sodium bisulfite, ascorbic acid, formamidinesulfinic, Tin ion, Fe (II) or Cu (I). The biocompatible reducing agent is preferably a tin salt, such as. As tin chloride or tin tartrate.

Of the Term "lyophilized" is used in its conventional Meaning used, namely in terms of a freeze-dried, preferably produced in a sterile manner Connection.

By the term "antimicrobial preservative" is meant an agent which inhibits the growth of potentially harmful microorganisms such as bacteria, yeasts or molds Depending on the dose, the antimicrobial preservative may also have some bactericidal properties However, microorganisms in the radiopharmaceutical composition are also sometimes used to block the growth of potentially harmful microorganisms in one or more components of non-radioactive kits prior to reconstitution Preservatives include: the parabens, ie, methyl, ethyl, propyl, or butylparaben, or mixtures thereof; benzyl alcohol; phenol; cresol; cetrimide and thiomersal u volatile to survive the lyophilization (z. Benzyl alcohol or phenol), or have very low water solubility. This poses a problem for their incorporation into a lyophilized kit designed to reconstitute with an aqueous solvent to yield a radiopharmaceutical solution. In addition, certain antimicrobial preservatives may form metal complexes with ^99m Tc, thereby adversely affecting the radiochemical purity (RCP) and thus the biodistribution of ^99m Tc-tetrofosmin. Furthermore, the presence of an antimicrobial preservative in the formulation increases the risk of problems of chemical incompatibility in kit storage, e.g. Due to the oxygen or sulfur abstraction by the phosphines of tetrofosmin.

Such kits are designed to give sterile radiopharmaceutical products suitable for administration to humans, e.g. B. via direct injection into the bloodstream. The lyophilised kit is to be reconstituted with sterile ^99m Tc-pertechnetate (TcO ₄ ^-) solution designed from a ^99m Tc radioisotope generator to give a solution which can be administered without further handling to a human. The ^99m Tc pertechnetate solution is provided in a biocompatible carrier. The "biocompatible carrier" is a fluid, particularly a fluid, in which the radiopharmaceutical is suspended or dissolved so that the composition is physiologically compatible, meaning that it can be delivered to the body of a mammal without causing toxic effects or excessive For convenience, the biocompatible carrier is an injectable carrier fluid, such as sterile, pyrogen-free injectable water; an aqueous solution, such as saline (which can be advantageously balanced so that the final product for injection is either isotonic or non-hypotonic), an aqueous solution one or more substances for regulating tonicity (eg salts of plasma cations with biocompatible counterions), sugars (eg glucose or sucrose), sugar alcohols (eg sorbitol or mannitol), glycols (eg glycerol ) or other nonionic polyol materials (e.g., polyethylene glycols, propylene glycols and the like). The biocompatible carrier can also be biocompatible organic solvents such. For example, include ethanol. Such organic solvents are useful to solubilize more lipophilic compounds or formulations. Preferably, the biocompatible carrier is pyrogen-free injection water, isotonic saline solution or aqueous ethanol solution. As indicated above, the pH of the biocompatible carrier for intravenous injection is suitably in the range of 4.0 to 10.5. The biocompatible carrier preferably comprises an aqueous solvent, more preferably isotonic saline. The use of the biocompatible carrier of the present invention is in the absence of an antimicrobial preservative.

The Kits of the present invention comprise a suitable container which contains the composition of the first embodiment. The Tetrofosmin can be either in the form of a free base or an acid salt or in the form of a complex of tetrofosmin and a non-radioactive Metal present, after the addition of technetium a transmetalation (i.e., a metal exchange), from which the desired product arises. Preferably, the tetrofosmin is in the form of a free Base before. Suitable containers are those that are sealed and therefore the preservation of sterile integrity and / or enable radioactive safety, optionally plus an inert headspace gas (eg, nitrogen or argon) while they are also allow the addition and removal of solutions by syringe. Such a preferred container is a vial sealed with septum, being gas-tight Closure with a seal (typically aluminum) is crimped. Own such containers the additional Advantage that the closure can withstand a vacuum, if desired z. B. for the purpose of change of headspace gas or for degassing solutions.

Of Further, the non-radioactive kits may contain additional ones Components, such as a transchelator, a pH regulator or a filling substance. A "transchelator" is a compound that reacts quickly to a weak complex with technetium and then depleted by the ligand becomes. This minimizes the risk of being reduced hydrolyzed Technetium (RHT), due to the rapid reduction of pertechnetate, which competes with technetium complex formation. Suitable transchelators are salts of organic acids with a biocompatible cation, in particular "weak organic acids" with a pKa in the Range from 3 to 7 acetic acid, Citric acid, Tartaric acid, gluconic, glucoheptonic, benzoic acid, Phenols or phosphonic acids are suitable weak organic acids. Therefore it is suitable salts include acetates, citrates, tartrates, gluconates, Glucoheptonates, benzoates, phenolates or phosphonates. preferred Salts are tartrates, gluconates, glucoheptonates, benzoates or phosphonates, particularly preferred phosphonates, most preferably diphosphonates. A preferred transchelator is a salt of gluconic acid, with a biocompatible cation, especially sodium gluconate. An additional one preferred transchelator is 5-sulfosalicylic acid or a salt thereof with a biocompatible cation. There is a possibility to use two or more trancelarators in combination, and the Tetrofosmin kits of the present invention are particularly preferred a combination of sodium 5-sulfosalicyclate and sodium gluconate.

Under The term "pH regulator" is a compound or to understand a mixture of compounds which (s) to ensure Serves to adjust the pH of the reconstituted kit for administration to humans or mammals within acceptable limits (from approximately 4.0 to 10.5). To the suitable pH-regulating agents counting pharmaceutically acceptable buffers such as tricine, phosphate or TRIS [i.e. H. Tris (hydroxymethyl) aminomethane] and pharmaceutically acceptable Bases such as sodium carbonate, sodium bicarbonate or mixtures thereof. A preferred pH control agent for the tetrofosmin kits of present invention is sodium bicarbonate.

Under The term "filler" is a pharmaceutical acceptable filler to understand the handling of the material during production and lyophilization can facilitate. Suitable fillers include inorganic Salts such as sodium chloride and water-soluble sugars or sugar alcohols such as Sucrose, maltose, mannitol or trehalose. Certain pH regulators can also as a filler act. A preferred filling substance with such a dual function represents sodium bicarbonate. Preferred kits of the present invention comprise a filler to facilitate lyophilization. A preferred filling substance for the Tetrofosmin kits In the present invention, sodium bicarbonate is a filler with dual function.

It has been found that the incorporation of a radioprotectant in the kits of the present invention provides the advantage that the ^99m Tc-tetrofosmin complex, with good radiochemical purity and post-reconstitution, has good stability up to 12 hours after preparation, without the need for Air supply step, which is taught by both the prior art as well as the instructions for use on the Myoview ^™ -Packung. This is a useful simplification because a process step is eliminated, thereby eliminating a handling process, resulting not only in a reduced dose of radiation to the operator but also in a faster and easier implementation. Furthermore, the step of air supply in the radiopharmaceutical practice is somewhat unusual and therefore there is a risk that it will be accidentally forgotten, with consequent detrimental effect on radiochemical purity.

The concentration of the radiation protection agent for use in the kits of the present invention is suitably 0.0003 to 0.7 molar, preferably 0.001 to 0.07 molar, especially before zugt to 0.0025 to 0.01 molar. For ascorbic acid this corresponds to a suitable concentration of 0.05 to 100 mg / cm ³ , preferably 0.2 to 10 mg / cm ³ , particularly preferably 0.4 to 1.5 mg / cm ³ .

When the ^99m Tc-tetrofosmin radiopharmaceutical of this invention is administered to a human, an appropriate amount of radioactivity to be used ranges from 185 to 1221 MBq (5-33 mCi). For imaging from the heart, the first dose should be 185-444 MBq (5-12 mCi), with 555-1221 mBq (15-33 mCi), given the same day, with rest and exercise injection on the same day is given approximately 1 to 4 hours later. Therefore, the initial ^99m Tc activity in the stabilized ^99m Tc radiopharmaceutical compositions of the present invention is in the range of 0.2 to 100 GBq, allowing for multiple dosing from the same formulation, even taking into account the radioactive decay of ^99m TC.

The lyophilized kit of the present invention is preferably formulated such that the pH of the solution when reconstituted with water or saline is 8.0 to 9.2, more preferably 8.0 to 8.6. This means that the amount of pH regulator must be adjusted if the radioprotectant is ascorbic acid, which is an acid. This is necessary to ensure the optimal pH of the Kit for the ^99m Tc radiolabeling of tetrofosmin; Stability post-reconstitution and suitability for patient administration are maintained. A preferred kit formulation for a 30 ml vial model is set forth in Example 2 which illustrates that the amount of sodium bicarbonate must be significantly increased over the conventional Myoview ^™ 10 ml vial formulation. The inventors have found that in a 30 ml vial kit, increasing the amount of ascorbic acid to 5.5 mg / vial or reducing the sodium bicarbonate level to 10 mg / vial results in freeze-dried cakes with an unacceptable visual appearance. The reason for this is believed to be the low glass transition temperature of ascorbic acid (-54 ° C), which is likely to lower the glass transition temperature of the formulation. Therefore, there is an upper limit to the amount of ascorbic acid that can be added if an acceptable lyophilized kit is to be prepared. It has been found that significantly higher sodium bicarbonate levels are needed to meet ascorbic acid and continue to yield an acceptable lyophilized plug.

The radiation protection agents of the present invention are commercially available from a number of suppliers. Tetrofosmin can be prepared as described by Chen, et al. [Zhong. Heyix. Zazhi, 17 (1) 13-15 (1997)] or by Reid, et al. [Synth. Appl. Isotope. Lab. Corp., Vol. 7, 252-255 (2000)]. The usual synthesis involves first preparing 1,2-bis (phosphino) ethane or H ₂ PCH ₂ CH ₂ PH ₂ followed by the addition of free radials of excess ethyl vinyl ether using a free radical initiator as described in Example 1.

In a second aspect, the present invention provides a multi-dose kit comprising the lyophilized formulation of the first embodiment in a sealed, sterile container equipped with a closure that allows for the addition and withdrawal of solutions while he preserves sterile integrity; the kit being formulated to allow 4 to 30 patient doses of ^99m Tc-tetrofosmin radiopharmaceutical to be obtained from a single multi-dose kit.

The multi-dose kit must be robust enough to withstand significantly higher levels of radioactivity and larger volumes of solution than traditional Myoview ^™ kits. Containers suitable as multi-dose vials preferably have a volume of from 20 to 50 cm ³ , more preferably from 20 to 40 cm ³ and most preferably from 30 cm ³ . The container is provided with a gas-tight seal into which multiple times with an injection needle can be inserted (for example, a seal closure from a crimped septum).

The multi-dose kit will provide sufficient material (e.g., up to 100 GBq ^99m TC per vial) for multiple patient doses, allowing for the possibility of matching patient dosage ^units in clinical grade syringes at various time intervals during the useful life of the stabilized preparation to the clinical situation. Alternatively, a unit dose of ^99m Tc-tetrofosmin radiopharmaceutical may be provided in a sealed container as discussed above. By the term "patient dosage unit" or "unit dose" is meant a radiopharmaceutical ^99m Tc-tetrofosmin composition having a radioactive ^99m Tc content which is suitable for in vivo imaging following administration to a single patient. Such "dosage units" are further described in the fifth embodiment (below) The multi-dose kits of the present invention are formulated to provide from 4 to 30, preferably 6 to 24 such dosage units of ^99m Tc-tetrofosmin radiopharmaceutical, however, in a reproducible manner with a series of ^99m Tc generator ^eluates It may also be possible to use the multi-dose kit in such a way that it gives 1 to 40 and possibly even more than 40 such dosage units.

As with the first embodiment, the multi-dose kit of the second embodiment does not require an air supply step in the reconstitution protocol, which is an important advantage. Moreover, the multi-dose kit of the present invention allows for much shorter production times for multiple radiopharmaceutical ^99m Tc-tetrofosmin preparations, resulting in a significantly reduced dose of radiation to the operator. The multi-dose kit also has an increased shelf stability of at least 78 weeks, whereas the conventional Myoview ^™ kit has a shelf life of 37 weeks. Further advantages of the multi-dose kit are set forth with respect to the method of the third embodiment (below).

• (i) Rekonstituieren des Mehr-Dosen-Kits der zweiten Ausführungsform entweder mit einer sterilen Lösung aus ^99mTc-Pertechnetat oder zunächst mit einem biokompatiblen Träger, gefolgt von einer sterilen Lösung aus ^99mTC-Pertechnetat;
• (ii) gegebenenfalls Ausführen von Schritt (i) in Anwesenheit eines antimikrobiellen Konservierungsmittels;
• (iii) Ermöglichen, dass eine ^99mTc-Tetrofosmin-Komplexbildung stattfindet, damit sich eine Lösung ergibt, die einen Großvorrat des gewünschten ^99mTc-Tetrofosmin-Radiopharmakons umfasst;
• (iv) gegebenenfalls Überprüfen der radiochemischen Reinheit des Großvorrats an ^99mTc-Tetrofosmin-Komplex;
• (v) Entnehmen einer Dosiseinheit aus dem Großvorrat aus Schritt (iii) in eine zweckmäßige Spritze oder einen zweckmäßigen Behälter;
• (vi) Wiederholen von Schritt (v) mit einer zusätzlichen Spritze oder einem zusätzlichen Behälter zu späteren Zeitpunkten, damit sich weitere Dosiseinheiten ergeben.

In a third aspect, the present invention provides a method of preparing a plurality of patient dosage ^{units of} the radiopharmaceutical ^99m TC tetrofosmin comprising:

• (i) reconstituting the multidose kit of the second embodiment with either a sterile solution of ^99m Tc pertechnetate or first with a biocompatible carrier, followed by a sterile solution of ^99m Tc pertechnetate;
• (ii) optionally carrying out step (i) in the presence of an antimicrobial preservative;
• (iii) allowing ^99m Tc-tetrofosmin complex formation to occur, resulting in a solution comprising a bulk supply of the desired ^99m Tc-tetrofosmin radiopharmaceutical;
• (iv) optionally checking the radiochemical purity of the bulk supply of ^99m Tc-tetrofosmin complex;
• (v) withdrawing a unit dose from the bulk supply of step (iii) into a convenient syringe or convenient container;
• (vi) repeating step (v) with an additional syringe or additional container at later times to provide additional dosage units.

The Dose unit is the same as with respect the first embodiment (above), and is more detailed in the fourth embodiment (below). Also the biocompatible carrier and preferred embodiments the same are the same as with respect the first embodiment (above) defined. A preferred biocompatible carrier for this Method is sterile saline solution. Preferably takes place the implementation of the method in the absence of an antimicrobial preservative.

The sterile ^99m Tc pertechnetate solution is preferably recovered from a technetium generator. The radioactive content of the ^99m Tc pertechnetate to be used in step (i) is suitably in the range of 2 to 100 GBq, preferably 5 to 75 GBq. The radioactive concentration of ^99m Tc is preferably not more than 10 GBq / cm ³ , more preferably not more than 2.5 GBq / cm ³ . Once manufactured, the bulk supply of the desired ^99m Tc-Tetrofosmin radiopharmaceutical has a shelf life of up to 12 hours.

The ^99m Tc tetrofosmin complex formation, ie, step (iii), is usually complete within 15 minutes at room temperature.

• (a) die Anzahl der Handhabungsvorgänge, welche Radioaktivität (^99mTc-Pertechnetat) involvieren, wird signifikant verringert;
• (b) ein Luftzuführungsschritt ist nicht notwendig;
• (c) es sollte nur eine einzige QK-Bestimmung pro Charge Dosiseinheiten erforderlich sein gegenüber einer QK-Bestimmung pro Dosis;
• (d) das Großmengen-Fläschchen wird in solch einer Weise formuliert, dass die Formulierung einer Reihe von ^99mTc-Generatoreluat-Bedingungen standhalten kann;
• (e) weniger Schritte sind involviert, weshalb sich die Automation einfacher gestaltet;
• (f) weniger nicht-radioaktive Kit-Fläschchen werden benötigt, was Kühllagerraum spart.

The method of the present invention has the following advantages over the alternative of reconstituting multiple Myoview ^™ 10 ml vials:

• (a) the number of manipulations involving radioactivity ( ^99m Tc pertechnetate) is significantly reduced;
• (b) an air supply step is not necessary;
• (c) only one single QC determination should be required per batch of dose units versus one QC determination per dose;
• (d) the bulk vial is formulated in such a manner that the formulation can withstand a range of ^99m Tc generator ^eluate conditions;
• (e) fewer steps are involved, which makes automation easier;
• (f) fewer non-radioactive kit vials are needed, saving cold storage space.

For the operator make a shorter one Processing time (i.e., more efficiency) and a reduced radiation dose the more important consequences are the more important Number of dosage units to be prepared fails.

• (i) den ^99mTc-Komplex von Tetrofosmin in einem biokompatiblen Träger;
• (ii) ein Strahlenschutzmittel mit einer Konzentration von 0,5 bis 6,0 mmolar, das ausgewählt ist aus Ascorbinsäure oder einem Salz davon mit einem biokompatiblen Kation;

mit der Maßgabe, dass die radiopharmazeutische Zusammensetzung kein antimikrobielles Konservierungsmittel enthält.In a fourth aspect, the present invention provides a stabilized radiopharmaceutical composition comprising:

• (i) the ^99m Tc complex of tetrofosmin in a biocompatible vehicle;
• (ii) a radiation protection agent having a concentration of 0.5 to 6.0 mmolar selected from ascorbic acid or a salt thereof with a biocompatible cation;

with the proviso that the radiopharmaceutical composition does not contain an antimicrobial preservative.

The "biocompatible Carrier "and preferred embodiments of the same are as defined above.

At a millimolar (mmololar) concentration, 1.0 mmolar is equal to 0.001 molar. The concentration of the radiation protection agent is preferably in the range from 0.6 to 5.7 mmolar, particularly preferably from 0.7 to 5.5 mmolar. These ranges correspond to those concentration ranges obtained when the preferred kits of the first embodiment are reconstituted with the required volume range of ^99m Tc perechnetate in saline. In addition, these concentrations of the radioprotectant are lower than those used in the Myoview ^™ "conjugate" solution formulation available in Japan.

preferred Radiation protection for the stabilized composition are the same as with respect to first embodiment Are defined.

Prefers the pH of the stabilized composition is in the range from 7.5 to 9.0, more preferably from 8.0 to 8.6.

In a fifth aspect, the present invention provides a patient ^{dosage unit of} the radiopharmaceutical ^99m Tc-tetrofosmin comprising the composition of the fourth embodiment having a ^99m Tc radioactive content suitable for single patient imaging.

The Patient dose unit is as in the first embodiment and is more suitable for administration to humans, sterile form in a convenient container or a convenient syringe to disposal posed. Such syringes are suitable for clinical use and are preferably disposable syringes, so the syringe never comes with more than one patient would be used. If necessary, the Be provided with a syringe shield syringe to the operator to protect against a radiation dose. Suitable radiopharmaceutical syringe labels are commercially available and preferably comprise either lead or tungsten as described by Logan [J. Nucl. Med. Technol., 21 (3), 167-170 (1993)].

Alternatively, the unit dose of ^99m Tc-tetrofosmin radiopharmaceutical may be provided in a container having a seal suitable for multiple puncture with an injection needle (e.g., a crimp seal in the form of a flared septum). The dosage unit of the present invention is preferably provided in a clinical grade syringe and most preferably is equipped with a syringe shield.

The radioactive ^99m Tc content of the dosage unit is suitably 150 to 1500 MBq, preferably 185 to 1250 MBq. If same-day rest and exercise injection are given, the first dose should be 185-450 MBq, followed 1-4 hours later by a second dose of 550-1250 MBq. The compositions preferably used in the dosage unit are as described in the third embodiment (above).

The Invention is illustrated by the non-limiting examples, which are detailed below.

Example 1 illustrates the synthesis of tetrofosmin. Example 2 depicts a lyophilized multi-dose or "bulk" kit of the present invention having a preferred model referred to as Myoview 30. Example 3 shows how a multi-dose lyophilized or "bulk" kit of the present invention is used to prepare several Dosing units of ^99m Tc-tetrofosmin can be used. Example 4 illustrates that radiophosphorus-containing lyophilized kits post-reconstituted with ^99m Tc pertechnetate have excellent radiochemical purity over many hours.

Example 5 demonstrates that in the Myoview30 kit, even without an air delivery step, stability post-reconstitution at increasing radioactive concentrations (RACs: Radioactive Concentrations) is higher than in Myoview ^TM . In addition, Example 5 illustrates that the Myoview30 kit can be successfully used at a wider range of elution intervals for the ^99m Tc generator. With regard to both the radioactive concentration (RAC) and ^99m Tc generator elution interval ranges, the kits of the present invention have useful flexibility, particularly with respect to a radiopharmaceutical process, where several ^99m Tc-tetrofosmin preparations per Day must be made.

Example 6 demonstrates that the Myoview30 kit of the present invention allows much shorter production times for multiple radiopharmaceutical ^99m Tc-tetrofosmin preparations, with substantially reduced operator radiation dose. Although the amount of radioactivity used for the QC sample is the same for Myoview30 and Myoview ^™ , Myoview30 involves 70% less time and 75% less radioactivity. In addition, it is easier for the operator to place four chromatography strips behind a radiation shield for quality control than sixteen.

From Example 7, it can be seen that a multi-dose vial of the present invention is useful for preparing thirty ^99m Tc-tetrofosmin dosage units while maintaining satisfactory radiochemical purity and without compromising the sterility of the vial contents. Thus, the radiochemical purity corresponded to twelve hours post-reconstitution of the specification, even after the plug had been stuck several times. There was no growth in the culture medium after twelve hours and the product passed the USP / Ph. Eur. Sterility test. The tested preparation dilutions showed a content of bacterial endotoxins below 313 IU / vial. This means that no viable bacteria or degradation products thereof have been detected and, therefore, the multi-dose vial functions efficiently without the need for an antimicrobial preservative.

Out Example 8 shows that the closures of the multi-dose vials of the present invention can withstand up to thirty-five needle punctures. Example 9 illustrates that multi-dose vials of the present invention a non-radioactive service life of 78 weeks (18 months) own when at 5 ° C (2 ° C to 8 ° C) stored and protected from light become.

Out 1 It is apparent that the radioprotectant compositions of the present invention provide a satisfactory radiochemical purity of greater than 95% to as much as twelve hours post-reconstitution (ie, shelf-life of the formulation).

2 shows the results from a comparison of the rate of loss with respect to the radiochemical purity of ^99m Tc-tetrofosmin over time, as a function of radioactive concentration (RAC) in Myoview30 and Myoview ^™ (with air supply). It can be seen that the Myoview30 kit of the present invention is much more robust.

Example 1: Synthesis of tetrofosmin

All Reactions and handling operations were carried out either in vacuo or under an oxygen-free nitrogen atmosphere. The solvent were dried and degassed before use with nitrogen purge. α-azoisobutyronitrile (AIBN) and ethyl vinyl ether were each obtained from BDH and Aldrich. Bis (diphosphino) ethane was prepared according to the literature [Inorganic Synthesis, Vol. 14, 10].

A Fischer pressure bottle equipped with a Teflon ^™ stir bar was charged with ethyl vinyl ether (5 cm ³ , 52.3 mmol), bis (diphosphino) ethane (1 cm ³ , 10 mmol) and α-azo-isobutyronitrile (0.1 g, 0.61 mmol). Thereafter, the reaction mixture was stirred and heated at 75 ° C for 16 hours. After cooling back to room temperature, the viscous liquid was transferred to a 50 cm ³ round bottom flask. Volatile materials were removed by heating under vacuum. The resulting nonvolatile material was pure by NMR. Yield: 3.0 g, 80%.
¹ H NMR (CDCl ₃ ): δ 1.12 (12H, dt J = 1.16 Hz, 7.15 Hz, OCH ₂ CH ₃ ) 1.51 (4H, br m, PC ₂ H ₄ P), 1 , 7 (8H, br t, J = 7.4 Hz, PCH ₂ CH ₂ OEt), 3.4 (8H, dt J = 1.16 Hz, 7.15 Hz, OCH ₂ CH ₃ ), 3.49 (8H; br m; PCH ₂ CH ₂ OEt) ppm.
³¹ P NMR: δ -33.17 ppm.

at Room temperature, tetrofosmin was converted to Tetrofosminsulfosalicylat by reaction with 2.3 to 2.5 molar equivalents of 5-sulfosalicylic acid in ethanol, followed by recrystallization from ethanol / ether.

Example 2: Formulation and Preparation a lyophilized bulk vial kit

An optimized formulation for making a 30 ml bulk vial is as follows: tetrofosmin 0.69 mg, Tin chloride dihydrate 90 μg, Dinatriumsulfosalicylat 0.96 mg, Sodium D-gluconate 3.0 mg, ascorbic acid 5.0 mg, sodium 11.0 mg, pH after reconstitution with 8.3 to 9.1. Saline

These Wears kit formulation the name "Myoview30".

It the production of 500 ml batches was carried out. So, nearly 90% Total Water Injection Water (WFI) placed in a preparation vessel. By rinsing with nitrogen, the injection water was freed from oxygen. Tetrofosmine sulfosalicylate, stannous chloride dihydrate, sodium D-gluconate, ascorbic acid and Sodium bicarbonate was dispensed, added and the Serially resolved with constant mixing. The dispensing cups were rinsed with deoxygenated injection water. Under With continuous mixing, the bulk solution was deoxygenated Injection water regulated to 100% of the final volume. The nitrogen purge was not continued. While of the remaining manufacturing process, a nitrogen blanket in the headspace applied.

The solution was sterile filtered, and 3.0 ml of the filtered solution became in 30 ml vials dispensed. The vials were partially plugged and then lyophilized.

Example 3: Method of reconstitution Radiation-containing bulk kit

A 30 ml vial of the Myoview30 kit (from Example 2) was placed in a convenient container with radiation-proof shield and the rubber septum was disinfected by means of a swab soaked in isopropyl alcohol. A sterile needle (the vent needle) was inserted through the rubber septum. ^99m Tc-pertechnetate generator eluate [with a volume of 10-30 cm ³ ; diluted with sodium chloride injection, USP as appropriate, without bacteriostat; at a radioactive concentration of up to 10 GBq / cm ³ and a radioactive ^99m Tc total content of up to 100 GBq (2.7 Ci)] was added using a shielded sterile syringe. Then the ventilation needle was removed. The contents of the reconstituted vial were gently mixed for ten seconds to ensure complete dissolution of the lyophilized powder and then incubated at room temperature for fifteen minutes.

The reconstituted Myoview30 vials was stored at 2-25 ° C, and the contents were within twelve hours of preparation used. Taken aliquots were also stored at 2-25 ° C and within the same 12-hour period like the reconstituted Myoview30 vial.

Example 4: Radiochemical Analysis of Radiochemical purity of a radiation-containing lyophilized Kits over time

Radiochemical purity of the Kits over time

The radiochemical purity [RCP] of the reconstituted Myoview30 kit (Example 2) was measured by two chromatographic systems: System 1: Stationary phase: ITLC-SG Mobile phase: Acetone / dichloromethane [35:65 v / v]

This system causes the lipophilic ^99m Tc tetrofosmine to be separated from the ^99m Tc hydrophiles and the lipophilic impurities [Species B, C and X] and ^99m Tc pertechnetate. System 2: Stationary phase: Whatman no paper Mobile phase: Acetonitrile / water [50:50 v / v]

This System causes the separation of reduced hydrolyzed technetium [RHT], which remains at the beginning of the strip, from the other technetium complexes, the hiking.

The Myoview30 vial was reconstituted without the use of an air delivery step. Results for the reconstitution of a Myoview30 vial with ^99m Tc pertechnetate (37.9 GBq in 17.5 ml, RAC = 2.2 GBQ / ml) are in 1 listed.

Example 5: Radiochemical analysis of Radiochemical purity of a radiation-containing lyophilized Kits over time, compared with the prior art

Myoview ^™ kits were obtained from Amersham plc (now part of GE Healthcare). The stability of the Myoview30 kit formulation of the present invention and that of the commercially available Myoview ^™ 10 ml kit formulation post-reconstitution with increasing radioactive concentration (RAC) were compared. With regard to Myoview ^™ , the reconstitution procedure was carried out according to the package insert, ie the air feed step was performed.

The study was based on eight Myoview ^™ preparations and eighty-nine Myoview30 preparations. Myoview ^™ vials were reconstituted at up to 4.5 GBq / ml and Myoview30 vials at up to 11.0 GBq / ml. All of the eight Myoview ^™ preparations were reconstituted with eluate from a ^99m Tc generator, eluting within a 24 hour elution interval. In contrast, the Myoview30 vials were reconstituted with eluate from ^99m Tc generators at various elution intervals, up to 96 hours without the use of an air delivery step. The results are in 2 listed.

Example 6: Comparison of Preparation Time and Radiation Dose for the Operator in Myoview30 and Mvoview ^™

• Verfahren 1: Rekonstituieren von vier Myoview30-Fläschchen (aus Beispiel 2) mit jeweils 74 GBq ^99mTc-Pertechnetat;
• Verfahren 2: Rekonstituieren von sechzehn Myoview^TM-Fläschchen mit jeweils 18,5 GBq ^99mTc-Pertechnetat.

Sixteen unit doses of 18.5 GBq (500 mCi) each of ^99m Tc tetrofosmin were prepared by one or the other of the following methods:

• Method 1: Reconstitute four Myoview30 vials (from Example 2) each with 74 GBq of ^99m Tc pertechnetate;
• Method 2: Reconstitute sixteen Myoview ^™ vials with 18.5 GBq each of ^99m Tc pertechnetate.

The results are listed in Table 1: method Relative radiation dose on the hands of the operator Connection time (min) QC time (min) Total time for preparation (min) 1 88 11 2 13 2 175 28 7 35

Example 7: Evidence of Sterility of a Multi-dose vial

Three separate batches of Myoview 30 prepared as described in Example 2 were examined. Immediately prior to reconstitution, each of the two vials from the three Myoview 30 ml batches was fitted with a BD Microlance 21 G ventilation needle, fitted with a 0.22 μm sterile and pyrogen free Millex GP filter. The vials were reconstituted with 23 ml of sterile saline. Immediately thereafter, diluted ^99m Tc eluate (2 ml) was injected into the vials so that the radioactive content was about 2 GBq / vial. At 25 ° C, the vials were stored for twelve hours. After fifteen minutes, the vials were treated as shown in Table 2. Table 2 Time post-reconstitution (hours) Exhausted volume (ml) of the simulated dose Total number of withdrawn single doses 0.25 0.25 10 6 0.5 10 12 1 10

So were thirty simulated doses after 15 minutes, 6 hours and at the end of shelf life, So after 12 hours, taken. The doses were used of 1 ml BD (Becton Dickinson) syringes taken with the needles BD Microlance 25 G were assembled. For each withdrawal became one fresh syringe / needle used. The doses number 1 and 21 were sent to radiochemical purity for analysis. The last dose (Number 30) was added to the LAL test (limulus amoebocyte lysate for determination bacterial endotoxins) and for the study of osmotic pressure cleverly. That after 12 hours in the Myoview30 vial remaining volume, namely nearly 7.5 ml, according to the current USP / Ph.Eur test for sterility. That's how it became the remaining volume divided by two, the sterility tests were performed and incubated in thioglycollate medium for 14 days (TGY) and tryptone soy broth (TSB) in 25 ° C and 32 ° C incubators.

LAL test

dose Number 30 of each vial was sent for testing for bacterial endotoxins. Of the Contents of the vials was initially with 25 ml of sterile saline reconstituted. Further dilution was carried out by 0.1 ml of this solution and added to 9.9 ml of injection water (WFI). Of the LAL test was carried out by the tube method. At this dilution the limit was for bacterial endotoxins to 313 IU / vial.

Results

• Sterility: As a result, it was stated that the product passes the sterility test (Pass = P) if no growth occurs in the culture medium.
• RCP: For all preparations, the radiochemical purity of ^99m Tc-tetrofosmin was 96-97%.
• pH: The pH of each vial was measured to be 8.2.
• LAL: As result for each of the vials it was stated that the product is made (P) if it is put Border corresponds.

The results are summarized in Table 3: Table 3: Summary of results for sterility and RCP stability charge GBq / vial n Time pr, hours sterility LAL / vial 1 2.05 0.25 N / A N / A 2.04 N / A 12 P P P P 2 1.95 0.25 N / A N / A 1.83 N / A 12 P P P P 3 1.97 0.25 N / A N / A 2.06 N / A 12 P P P P Overall average N / A N / A P N / A NA = not executed, P = passed

Example 8: Proof of the closure integrity of a Multi-dose vial

At the used Myoview30 closure was PH 701/45 red-brown (1178) and at the container around a 30 ml vial Type 1, bulkhead. Ten Myoview30 vials were prepared according to Ph.Eur.3.2.9 tested, except that instead of ten punctures as in Ph. Eur. thirty-five punctures were made. This was necessary to the increased Number of multiple doses of a multi-dose vial to simulate. Each closure was made thirty-five times using a fresh one Injection needle with an outer diameter punctured by 0.8 mm, with each puncture at a different location took place. The last puncture was at the same time an injection of ultrafiltered water up to the nominal volume of 30 ml. The ten filled ones phial with punctures were upright in a beaker with methylene blue solution (1 g / l) dipped. The external pressure was reduced by 270 mbar to 750 mbar for 10 minutes. Subsequently, the Ambient pressure restored, and the vials were submerged in the methylene blue solution, more thirty Rest for minutes. The vials were rinsed thoroughly and vor a white background checked for any discoloration. In the test was no penetration of dye into any of the vials demonstrated.

Example 9: Stability Study of Multi-dose Vials

Several vials of three separate Myoview30 batches, prepared as in Example 2, were protected from light and stored at a controlled temperature of 5 ° C. When stored for up to 52 weeks, vials were tested at intervals. Tetrofosmin, ascorbic acid, stanno, disodium sulfosalicylate, oxygen content and moisture content were assayed. The purity of tetrofosmine was monitored by ¹ H and ³¹ P NMR. The radiochemical purity of the ^99m Tc-tetrofosmin prepared using the stored kit was also measured at each time point.

All results obtained showed that the product, when stored protected from light at 5 ° C (2 to 8 ° C), met all specifications over the full 52 week period. All results were evaluated and a statistical analysis was performed. Quantitative parameters were subjected to a linear regression analysis to determine the relationship between each of the parameters and the storage time. The correlation coefficient obtained from the regression analysis was examined for significance using the Pearson test. The 95% confidence interval for an individual parameter was calculated. If the parameter could only decrease (or increase) over time, a one-sided confidence interval was calculated. The 95% confidence intervals and regression lines were extrapolated up to the 78th week (the 18th month), ie 6 months beyond the time period covered by the long-term data. This represents the maximum extension of shelf life based on the available results according to ICH (The International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) guideline Q1E. The earliest time at which the 95% confidence limit for the average intersects the proposed acceptability criterion is greater than the 78th week for samples stored at 5 ° C. Myoview30 lots stored for longer than 78 weeks in the form described had a radiochemical purity of over 90% when reconstituted with 5.5 to 89 GBq ^99m Tc pertechnetate twelve hours post-reconstitution.

Claims (16)

A lyophilized, non-radioactive kit which, when reconstituted with ^99m Tc pertechnetate solution, yields a stabilized radiopharmaceutical ^99m Tc tetrofosmin composition, the kit having a formulation comprising: (i) tetrofosmin; (ii) a radiation protection agent selected from ascorbic acid or a salt thereof with a biocompatible cation; (iii) a biocompatible reducing agent; (iv) a pH control agent in an amount effective to ensure that, upon reconstitution of the saline kit, the resulting solution has a pH in the range of 8.0 to 9.2; provided that neither the kit nor the radiopharmaceutical ^99m Tc tetrofosmin composition contains an antimicrobial preservative. A kit according to claim 1, which further comprises at least a transchelator selected from 5-sulfosalicylic acid and gluconic or salts thereof with a biocompatible cation. A kit according to claim 1 or 2, wherein the biocompatible Reductant comprises the tin ion. Kit according to one of claims 1 to 3, wherein the pH-regulating agent Sodium bicarbonate includes. A multi-dose kit comprising the lyophilized formulation of claims 1 to 4 in a sealed, sterile container equipped with a closure which allows the addition and removal of solutions while maintaining sterile integrity; the kit being formulated to allow 4 to 30 patient doses of ^99m Tc-tetrofosmin radiopharmaceutical to be obtained from a single multi-dose kit. Multi-dose kit of Claim 5, wherein the container is a sealed with a septum vial with a volume of 20 to 40 cm ^3. A method for producing a plurality of patient dosage ^{units of} the radiopharmaceutical ^99m Tc-tetrofosmin comprising: (i) reconstituting the multi-dose kit of claim 5 or 6 either with a sterile solution of ^99m Tc pertechnetate or first with a biocompatible carrier followed by a sterile solution of ^99m Tc pertechnetate; (ii) optionally carrying out step (i) in the presence of an antimicrobial preservative; (iii) allowing ^99m Tc-tetrofosmin complex formation to occur, resulting in a solution comprising a bulk supply of the desired ^99m Tc-tetrofosmin radiopharmaceutical; (iv) optionally checking the radiochemical purity of the bulk supply of ^99m Tc-tetrofosmin complex; (v) withdrawing a unit dose from the bulk supply of step (iii) into a suitable syringe or container; (vi) repeating step (v) with an additional syringe or additional container at later times to provide additional dosage units. The method of claim 7, wherein the ^99m Tc pertechnetate used in step (i) has a radioactive content in the range of 5 to 100 GBq. A stabilized radiopharmaceutical composition comprising: (i) the ^99m Tc complex of tetrofosmin in a biocompatible carrier; (ii) a radiation protection agent selected from ascorbic acid or a salt thereof having a biocompatible cation in a concentration of 0.5 to 6.0 mmolar; with the proviso that the radiopharmaceutical composition does not contain antimicrobial preservatives contains medium. A composition according to claim 9, wherein the radiation stabilizer concentration in the range of 1.4 to 5.5 mmolar. A composition according to claim 9 or 10, wherein the Radiation protection agent ascorbic acid is. A composition according to claim 9 or 10, wherein the Radiation protection agent is sodium ascorbate. A composition according to any one of claims 9 to 12, wherein the biocompatible carrier Saline solution. A composition according to any one of claims 9 to 13, wherein the radioactive content of the ^99m Tc is 150 to 850 MBq. The patient ^{dosage unit of} the radiopharmaceutical ^99m Tc-tetrofosmin comprising the composition of claims 9 to 14 in a clinical grade container or syringe, wherein the radioactive ^99m Tc content of the radiopharmaceutical is suitable for imaging a single patient. Patient dosage unit according to claim 15, which in a syringe provided with a syringe shielding member to protect the operator against a radiation dose.